linux-kernel - Re: [patch 09/17] Add all cpus option to stop machine run

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Message-ID: <20080409182454.GF30885@one.firstfloor.org>
Date:	Wed, 9 Apr 2008 20:24:54 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Alexey Dobriyan <adobriyan@...il.com>
Cc:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	akpm@...ux-foundation.org, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org, Andi Kleen <andi@...stfloor.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Jason Baron <jbaron@...hat.com>, Adrian Bunk <bunk@...sta.de>,
	Christoph Hellwig <hch@...radead.org>, akpm@...l.org
Subject: Re: [patch 09/17] Add all cpus option to stop machine run

On Wed, Apr 09, 2008 at 10:10:10PM +0400, Alexey Dobriyan wrote:
> I continue to think that all this so-called "immediate" infrastructure
> is an absolute overkill and declared D-cache line savings will _never_
> matter 

You are quite wrong on that.

> and will never be measured on real life workloads. Right now you
> claim 1 (one) cacheline saving in schedule() which can be trivially

That is just an example. Once the infrastructure is in a lot more
flags would move it into it. I think eventually most sysctls
should be immediate values for once.

> Also, my gut feeling of a guy who is also on receiveing end of bugreports
> at SWsoft that line with .text games was crossed by SMP alternatives and

You already lost -- Linux regularly rewrites itself. Ok not quite yet
but self modifying code is already wide spread and happens commonly
(e.g. with alternatives and some other cases) 

> 
> And bugs when CPU executed bullshit and silently rebooted.

So far nobody has seen that and the probably of it actually happening
is rather remote too.


> And so on.
> 
> 	Alexey, more and more liking OpenBSD
> 		where such games won't even
> 	        hit mailing lists

Maybe that is why Linux scales to large systems and OpenBSD 
doesn't ...

-Andi

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